Method of and apparatus for reactivating charcoal



5.; w. RICE METHOD OF AND APPARATUS FOR REACTIVATING CHARCOAL Filed Dec. 51

lug rgo L960' vce BY g ATTORNEYS WITNESES Patented May 13, 1930 mm .s'ra'rris PATENT oFFrcE wm'rm OI vonmsrnw YOR I mnon or urn arm-nus IIOB nmcrrva'mm Application ma. mem er :1, ms. Serial Io. 78,704.

The present method and'apparatns while capable of a fairly wide rangeof utility in the .arts, are peculiarly suited for the reactivation or revivificatmn of charcoal.

though various kinds of charcoal might be treated by the method, it is peculiarly adapted for the treatment of bone char, such as is commonly used for decolorizing sugar in the process of sugar refining, or fordecolorizing or unfyingoil or other substances.

n the sugar refining process for instance,

bone char is used as an adsorbent for re:

, moving foreign organic matter from the sugar being treated. It is customary to subsequently subject the char to a reactivating process inorder to remove this organic mat'-.

ter and render the char fit for reuse.

The conventional methods used in reactivatin have been unsatisfactory for a number 0 reasons. In the first place, the methods are expensive due to the fact that externally fired kilns are used and high temperatures maintained. In the second place, the treatment'which the char undergoes is an undesirable and, highly ineflicient one. The char is ordinarily passed through the highly heated kiln in the presence of iusulficient air-tosupport combustion, and the organic matter which has been adsorbed bythe char, is distilled ofi, resulting in, a heavy carbon deposit on the surface of the char which is subsequently burned off in a rather superficial manner.

By the use of my improved process and apparatus, the method is rendered much more economical, and the reactivated char which results from the method is of a better' quality.

In accordance with a preferred embodiment of the present invention, the kiln is internally fired, and the gases are recirculated, efiecting,

a considerable saving in fuel, also the precess is carried out at a rather low temperature and the char in its passagethrough the kiln encounters suflicient air to support actual combustion. Thus the organic matter is actually burned out of the char rather than distilled of, no carbon depositsare'formed,

and the treated char is more thoroughly re- *issupo activated and entirely free from clogging carbon deposits on its surface.

- The invention may be. more. fully understood from the following description in connection with ,the accompanying. drawing which is a somewhat diagrammatic view malnly in longitudinal section through a reactivating apparatus embed the present invention, and well suite forcarrying out the method. a I co In the accompanying drawing I havefused' the reference character 10 to designate a suitable base u n which an inlet chamber 11 Y -An inclined rotary kiln-12 whic may be of conventional construction has bearings at its upper end in the walls of the inlet chamber 11, and at its lower end in one wall of a fire box 13. Conventional driving mechanism me be employed for rotating the kiln, and been illustrated as a drlvenipinion 14 supported upon a base 15? and meshingwith a ring gear 16 fixed to the kiln. Supplemental supporting and driving means such as the friction rollers 17 may also be employed. Thekiln' is provided with the usual number of longitudinally extending flights 18 for thoroughly tumbling and agitating the char as the latter is passed through the. kiln.

A vertical ballle wall 19 in the fire box protects the discharge end of the kiln from receiving directly radiated heat from the burn er 20. This burner may use either gas or oil, and in any event 'is controlled by some means which can be manually or automatically'regulated for supplying air to the fuel mix- 1%5 shown, the burgir isdsuitable for gas, 111C udmgagasp1 an anmrpipe 22 the latter being proviyl ed with a controlling valve 23 for predetermining the amount of air delivered with the fuel mixture at the burner. In all cases more air is delivered than is ac tually necessary to support combustion at the burner,since is air is also used for supp0 combustion of the char passing throng the kiln.

From the chamber 11 there'rises aflue'24 referably, @equi ped with. an automatic Sam per 25 whic is controlled by the pressure in chamber-11. consist merely of a suitably weighted disc in the flue. The char or other material to be treated is delivered through a chute 26 to the upper inlet end of the kiln, and may be brought to the chute by a screw conveyor 27, or any other suitable mechanism.

Reference character 28 has been used to designate an air recirculation pipe extending from the upper end of chamber 11 back to the fire box 13. A suitable fan or blower 29 in the pipe maintains a positive recircula tion of gases back to the fire box, and the pipe may be controlled by a damper 30 introduced between-the chamber 11 and the fan.

The heated char discharging from the lower outlet end of the kiln, drops into a chute 31, and passing under a gate valve 32,

. is subjected to a cooling spray of water from any number of spray heads 33 mounted in steam escape pipes 34. Flap valve 32 pre-" vents the passage of steam upwardly into the fire box, and the cooled char passes under another gate valve 35 and through a chute 36 into a receptacle or storage bin (not shown).

The method may be outlined substantially as follows. The char to be reactivated 0r revivified is discharged through the chute 26 sorbed "by the char. Due to the presence of blower 29 and damper 25, there will be a recirculation of gases back through the recirculation pipe 28 to the fire box. Thodamper 25 of course, automatically opens to relieve pressures in the recirculation system, and when recirculation is undeslrable, it Wlll be a very easy matter, not only to stop the recirculation by closing 'damper30, but to quickly cool the kiln by the action of fan 29.

The temperature in the kiln is maintained relatively low, that is to say, approximately between 400 and 800 Fahrenheit. The char in its passage through the kiln is agitated and tumbled by the flights 18, so that by the 'time'the char has reached the discharge end of the kiln, the entire surface of the mass of material will have been properly exposed to the air and reactivated by the burning'out of the organic matter as above described. The hot char coming down the chute 31 and under the gate valve 32 is properly'cooled by the water spray at 33, and passes at a relatively low temperature through chute 36 to the stor-' age bin or other receptacle.

It is to be noted that by recirculatin the gases in the system I may be able to efi ect a considerable economy of fuel, and to main-.

'tain a substantially uniform temperature throughout the entire length of the kiln. It

is to be noted however, that this method does not necessarily comprehend therecirculation of gases, because I may efl'ect considerable economy over present processes even without the recirculation feature. One improved feature of the method whether recirculation is used or not, is the actual burning out of the with adsorbed organic matter which includes the step of slowlypassing the charcoal through a kiln, subjecting it in its passage through the kiln to -a"cont1nuous recirculation of pre-heated hot gases through the kiln I which will support the combustion of the organic matter.

2. A method of reactlvatlng charcoal laden with organic matter which includes the steps .of passing the charcoal through an internally fired kiln in which gases are flowing in a direction oppositeto the direction of movement of the charcoal, tumbling the charcoal in the kiln to expose all of'the surfaces thereof to the gases, and supplying suflicient I air to' the gases passing through the kiln to support combustion of the organic matter in thechar, thegas pressure in the kiln being below a -pr etermined amount.

A method of revivifyingbone char laden with adsorbed organic matter which includes the steps of maintaining a relatively rapld continuous'circulation of hot' air laden gases in a closed circuit, and passing the char relatively slowly through part of the circuitto burn the organic matter out 'of the char.

4. A method of .reactivating charcoal laden with adsorbed organic matter which includes the steps of slowly passing the charcoal through a kiln while malntaimng through the kiln a continuous relatively rapid recirculation of preheated hot gases contaming only suflicient oxygen to support the slow combustion of the organic matter.

EDGAR RICE. 

